FSA SL-K Light Crank Question.

I have a FSA SL-K Light crank with 170 crank arms and 52-39 chain rings. I came across a FSA SL-K Light compact crank with 172 crank arms and 50-34 chain rings. The crank is no good but the crank arms and chain rings are still good! Can I switch out the crank arms and chain rings to my FSA crank? Would everything match up?

Standard cranks (53/39) typically use a different bolt circle diameter (BCD) than compact cranks (50/34) so you probably can't swap chainrings. The drive side crank arm is integrated with the chainrings so you can't just swap crank arms and make a franken-crank out of the 50/34 parts.

Standard cranks (53/39) typically use a different bolt circle diameter (BCD) than compact cranks (50/34) so you probably can't swap chainrings. The drive side crank arm is integrated with the chainrings so you can't just swap crank arms and make a franken-crank out of the 50/34 parts.

In this particular case both the standard and compact versions have a BCD of 110mm and use a BB30 interface. So he CAN swap out the chainrings, but the crank arms are out of the question. Unless he just means the bearings are done - but then - there's nothing to swap over so I'm left with a big ????

Thanks for everyone's response! Was looking on a listing on E-Bay that had 50-34 chainrings and wanted to switch them with my standard 52-39 chainrings. Now I know the BCD is different (110mm-130mm) I will sell the standard crank and look for a compact crank! My bikes are older and do not have the option to use a BB30.